EP0773692A1 - Komprimierender Videoverstärker - Google Patents

Komprimierender Videoverstärker Download PDF

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Publication number
EP0773692A1
EP0773692A1 EP96202988A EP96202988A EP0773692A1 EP 0773692 A1 EP0773692 A1 EP 0773692A1 EP 96202988 A EP96202988 A EP 96202988A EP 96202988 A EP96202988 A EP 96202988A EP 0773692 A1 EP0773692 A1 EP 0773692A1
Authority
EP
European Patent Office
Prior art keywords
video amplifier
amplification
amplification circuit
circuit
feedback
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP96202988A
Other languages
English (en)
French (fr)
Other versions
EP0773692B1 (de
Inventor
Frédéric Heber-Suffrin
Philippe Vilard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Original Assignee
Philips Electronique Gran Public
Koninklijke Philips Electronics NV
Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Philips Electronique Gran Public, Koninklijke Philips Electronics NV, Philips Electronics NV filed Critical Philips Electronique Gran Public
Publication of EP0773692A1 publication Critical patent/EP0773692A1/de
Application granted granted Critical
Publication of EP0773692B1 publication Critical patent/EP0773692B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/68—Circuits for processing colour signals for controlling the amplitude of colour signals, e.g. automatic chroma control circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/648—Video amplifiers

Definitions

  • the arrangement which generates several voltages different from each other, is a cascade resistance divider, at the head of which a reference voltage is applied via a diode, and whose resistors further constitute the aforesaid second resistances of the amplification circuits.
  • the resistors of the divider have a double function, they constitute both a voltage divider and the second resistors of the amplification circuits.
  • An image display device is advantageously equipped with a video amplifier according to the invention described above.
  • An image display device receives signals which can be presented in several ways: with carriers in different frequency ranges, different types of modulation, etc. However, after appropriate demodulation, each of the colors of an image to be displayed is defined by a specific color signal. In general three basic colors are defined, red, green, and blue. We will speak of "red signal”, “green signal”, “blue signal”.
  • the collector of the first transistor is connected on the one hand to an output respectively R-OUT, G-OUT, B-OUT, and on the other hand, via a load resistance respectively RcR, RcG, RcB, to a voltage source 200V power supply, for example 200 volts, and its base is connected to a 12 V voltage source, for example 12 volts.
  • the resistors RcR, RcG, RcB are equal to each other, for a reason of dissipated power.
  • the second transistor is mounted with its base connected respectively to the R-IN, G-IN, B-IN inputs, and its collector connected to the emitter of the first corresponding transistor.
  • the outputs R-OUT, G-OUT, B-OUT are intended to be connected, in a known manner, for example to the cathodes of a screen tube not shown.
  • the emitter of a second transistor TR, TG, TB is connected to a first resistor, respectively R4R, R4G, R4B.
  • This first resistor is itself connected to a second resistor connected to a fixed voltage source which is here ground, this second resistor being respectively constituted by R3 + R2 + R1 for the transistor TR, by R2 + R1 for the transistor TG, and by R1 alone for the transistor TB.
  • the sets made respectively of resistances R4R + [R3 + R2 + R1] for the red, R4G + [R2 + R1] for the green, and R4B + R1 for the blue, constitute resistance to feedback.
  • a so-called definition circuit common for all of the colors, for establishing a reference value of the threshold, consists of the elements DZ, Rp and Tth.
  • a reference voltage is defined by a zener diode DZ, the anode of which is here connected to ground, and into which a current is introduced from a 12V supply voltage source of 12 volts via a resistor Rp.
  • This reference voltage is taken up by a bipolar transistor Tth mounted according to the so-called emitter follower assembly, the base of which is connected to the diode DZ and which comprises, in series between its emitter and the ground, the three resistors R3, R2, R1.
  • the arrangement of the resistors R3, R2, R1 thus provides several different voltages, at the different connection points: between R4R and R3 + R2 + R1, between R4G and R2 + R1, between R4B and R1, so that each of the amplification circuits sees a different threshold voltage, increasing for successively blue, green, and red.
  • the threshold voltage is applied, at each of the connection points, only when the base-emitter diode of the transistor Tth is conductive. This is the case, as long as the voltage at one of the above connection points does not reach the threshold voltage.
  • the operation is as follows, for example for the "red" amplification circuit: if the voltage at the connection point R, due to the red signal in the TR / TcR amplification circuit, is less than the voltage defined by DZ minus the base-emitter voltage of Tth, this diode is conductive, the part [R1 + R2 + R3] of the feedback resistance is short-circuited by the diode, and only the resistor R4R is in play.
  • a circuit which has given satisfaction includes transistors of the BF869 model for the TcR, TcG, TcB transistors, transistors of the BC858 model for the TR, TG, TB transistors, 150 ⁇ resistors for R4R, R4G, R4B, 10 k ⁇ for RcR, RcG, RcB, and resistors of 39 ⁇ , 15 ⁇ , 4.7 ⁇ for R1, R2, R3 respectively.
  • the DZ zener diode is a 2 volt model. Some of the values should be adapted slightly depending on the screen tube used.
  • the levels of the color signals applied to the tube must be different for the three colors. It was assumed that these levels had been adjusted by known means before being applied to the amplifier. This is important because the adequate value of the threshold, for which the feedback value takes a higher value, depends on the level reached by the signals, which differs according to their greater or lesser prior amplification.
  • the levels could also be adjusted in the amplifier itself, by giving the resistors R4R, R4G, R4B different values, that is to say by giving the three amplification circuits rates of different feedback. In this case, it is clear that the division ratio of the divider R1, R2, R3 must be adapted accordingly, the adequate values being able to be determined by means of routine tests.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)
  • Amplifiers (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Picture Signal Circuits (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
EP96202988A 1995-11-08 1996-10-28 Komprimierender Videoverstärker Expired - Lifetime EP0773692B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9513223A FR2740931A1 (fr) 1995-11-08 1995-11-08 Amplificateur compresseur video
FR9513223 1995-11-08

Publications (2)

Publication Number Publication Date
EP0773692A1 true EP0773692A1 (de) 1997-05-14
EP0773692B1 EP0773692B1 (de) 2000-05-10

Family

ID=9484362

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96202988A Expired - Lifetime EP0773692B1 (de) 1995-11-08 1996-10-28 Komprimierender Videoverstärker

Country Status (7)

Country Link
US (1) US5903320A (de)
EP (1) EP0773692B1 (de)
JP (1) JPH09215002A (de)
KR (1) KR100403496B1 (de)
DE (1) DE69608207T2 (de)
FR (1) FR2740931A1 (de)
MY (1) MY115874A (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005151468A (ja) * 2003-11-19 2005-06-09 Sanyo Electric Co Ltd アンプ

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4118731A (en) * 1976-07-19 1978-10-03 Rca Corporation Video amplifier with suppressed radio frequency radiation
EP0230924A2 (de) * 1986-01-29 1987-08-05 Blaupunkt-Werke GmbH Schaltungsanordnung zur Regelung des Arbeitspunktes von breitbandigen Videoendstufen
US5299000A (en) 1992-06-17 1994-03-29 Zenith Electronics Corp. Video white signal compression and peaking

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3619486A (en) * 1969-08-26 1971-11-09 Zenith Radio Corp Matrix amplifier for developing push-pull color control signals

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4118731A (en) * 1976-07-19 1978-10-03 Rca Corporation Video amplifier with suppressed radio frequency radiation
EP0230924A2 (de) * 1986-01-29 1987-08-05 Blaupunkt-Werke GmbH Schaltungsanordnung zur Regelung des Arbeitspunktes von breitbandigen Videoendstufen
US5299000A (en) 1992-06-17 1994-03-29 Zenith Electronics Corp. Video white signal compression and peaking

Also Published As

Publication number Publication date
JPH09215002A (ja) 1997-08-15
DE69608207T2 (de) 2000-12-21
DE69608207D1 (de) 2000-06-15
KR100403496B1 (ko) 2004-03-18
EP0773692B1 (de) 2000-05-10
FR2740931A1 (fr) 1997-05-09
US5903320A (en) 1999-05-11
MY115874A (en) 2003-09-30
KR970031907A (ko) 1997-06-26

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